Cluster analysis, Advanced Statistics

Cluster analysis: A set of methods or techniques for constructing a sensible and informative classi?cation of an initially unclassi?ed set of data, using variable values observed on each

individual. Essentially all such methods or techniques try to imitate what the eye-brain system does so well in the two dimensions; in the scatter plot shown in the figure given above36, for instance, it is very easy to detect the presence of three clusters without making the the meaning of the term ' cluster' explicit.